Family groups (5)
'groups' is the definition.
(more than one biological genus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for genera that I've seen before include "Types" , "Taxonomic categories (biology)" , "Forms" , "Blood vessel" , "Taxonomic groups" .)
'family groups' is the definition.
(I've seen this in another clue)
This is all the clue.
(Another definition for clans that I've seen is " Scots family group".)